Force-induced misfolding in RNA
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)Abstract
Under normal conditions RNA molecules fold into a biologically functional native structure. However, folding is a dynamical process governed by the competition between a large number of structures that may lead to misfolding. We investigate folding of RNA secondary structures in the presence of mechanical force by introducing a model that includes the minimal number of structures necessary to reproduce the phenomenology observed in single molecule pulling experiments. We consider a sequential dynamics at the level of individual base-pairs and include phenomenological corrections of entropic origin that account for the neglected structures. The model is capable of reproducing the pattern of unfolding and refolding force extension curves, the distribution of breakage forces and the misfolding probability obtained in single molecule force experiments. As an example, we reproduce results recently obtained in pulling experiments in the three-helix junction S15 RNA molecule (S15). We show that S15 undergoes force-induced misfolding where force favors the formation of a stable non-native hairpin.